Many fluids are transported in bulk containers, such as ISO tanks and shipping containers, railcar containers, 55 gallon drums and other bulk containers. Highly viscous fluids and fluids high in solids content present particular transportation problems, such as ease of discharge of a filled container.
Examples of high solids content fluids include pepper mash, fruit pulps, grape mash/musk, drilling muds, clay slurries, fish slurries, tomato products, inks, and paints. During transportation, a high solids content fluid can separate into a fluid portion and a solids portion. Upon arrival at the discharge location, the solids separation must be addressed. If the solids portion is dense, the solids will settle to the bottom of the container, requiring removal of the fluids from the top portion of the container and solids removal later. If the solids portion is light, the solids will float to the top and create a solids cap. While the liquid portion is easily discharged from the bottom of the container, the solids cap will remain and must be physically unloaded later. Unloading of the solids can be labor intensive, such as physically breaking up and shoveling the solids cap or solids bottom. To assist in unloading containers filled with high solids content, mechanical agitation has been utilized, such as by placing rotors, vanes or other types of mechanical agitators in the transport tank, or even rotating the entire container (see U.S. Pat. No. 3,132,846, incorporated herein by reference).
Air injection has also been a method of mixing (see U.S. Pat. No. 4,595,296 to Parks, incorporated herein by reference). In the Parks patent, a fluid filled tank has a gas injector (or injectors) fixed to the bottom of the tank connected to a distribution manifold within the tank. The injectors are attached to a source of suitable gas (air, nitrogen or other inert gas), and the gas pulsed into the injectors assist in fluidizing and homogenizing the liquid/solids stored in the tank. The gas injector generally includes a feed line and an accumulator plate positioned at the exit of the feed pipe to assist in shaping the released bubble shape.
Examples of highly viscous fluids include oils/lubricants, syrups, and resins. These types of fluids present discharge problems due to the inability of these fluids to easily flow, resulting in long discharge times. Discharge times can be decreased by heating the fluid, thereby lowering the viscosity and increasing the fluid flows. Generally, either the bottom of the container or the entire container will be heated. However, heat transport in a viscous fluid can be slow and inefficient, and hence, smaller containers, such as a 300 gallon container, are used to reduce the fluid volume to be heated. Even with these smaller containers, heat times and discharge times can still be excessive.
In certain circumstances, it is desirable to transport fluids in flexible bags in a fixed wall container. A disposable bag prevents damage/contamination to the transport container from the fluid and eliminates the need to clean the container after each use. For instance, transport bags are used to reduce the potential for tank contamination of the product when the transported fluid is food stuffs or food grade materials. In these instances, a transport bag can be constructed of food grade plastics and if needed, can be pre-sterilized prior to use. Additionally, transport bags can be used when transporting hazardous materials, thereby preventing contamination of the tank by the fluid. Bag transport of high solids fluids or viscous fluids, however, presents problems, as prior art mechanical agitation or air injection is generally not feasible due to the inability to position the agitation device into the interior of the bag.